Data collection has been completed for a case-control study of risk factors for the acute leukemias in adults in which patients can be classified according to clonal chromosome characteristics, immunologic phenotype, and other biochemical markers, as well as according to more widely available classification systems, to determine if risk factors differ for distinct subgroups of patients. The study was motivated by reports that 50 % of leukemia patients have chromosome abnormalities in bone marrow, and that these patients are likely to have had prior chemotherapy or occupational exposure to solvents. Approximately 650 patients (85% of those eligible) who were enrolled in cancer treatment protocols sponsored by Cancer and Leukemia group B, a cooperative cancer study group, were interviewed regarding exposure to solvents and chemicals, smoking, irradiation, use of potentially toxic medications, and family medical history. A total of 636 interviews were also completed with population controls, representing an 80% response rate. Data are currently being readied for analysis. Preliminary results suggest associations between cigarette smoking, marijuana use, and exposure to certain drugs and chemicals and leukemia risk. In a related ongoing study, nearly 250 additional patients with acute myelocytic leukemia who are being studied by Cancer and Leukemia Group B for the presence of specific oncogenes have also been interviewed. Among the fist 50 patients studied, a potential association has been found between Ras mutation and both cigarette smoke exposure and use of insecticides and pesticides.